Musical instruments with capacitative pickup



Nov. 2,0, 1956 l J. T. KUNZ 2,770,994

MUSICAL INSTRUMENTS WITH CAPACITATIVE PCKUP Filed sept. 21, 1951 IN VENTOR.

ATTORNEYS United States Patent O MUSICAL INSTRUMENTS WITH CAPACITATIVEPICKUP Jacob T. Kunz, North Hills, Pa., assignor to SchulmerichElectronics, Incorporated, Sellersville, Pa., a corporation ofPennsylvania Application September 21, 1951, Serial No. 247,585 Claims.(Cl. 84-1.14)

This invention relates to musical instruments and particularly to aninstrument having a plurality of vibrating elements or rods forproducing tones, such as true bell or chime tones and is especiallyuseful in instruments for the production of bell or chime music.

In an instrument of the type involved herein, the vibrations of the rodsare picked up electrically and amplified, modified, and then changedinto sound by a loudspeaker so as to produce bell music. Theamplification is high so that particular care must be taken to removeall undesirable tones and to modify the vibrations to produce thedesired partial relationship in each note.

One of the objects of the present invention is to provide an improvedbell tone instrument of simplified construction.

Another of the objects of the invention is to provide an improvedarrangement for obtaining the proper relationship of partials andstrength thereof for all of the rods or vibrators of an electric belltone instrument.

In one aspect of the invention, the vibrators are of the fixed-free typeand are mounted on a supporting block, the block being resilientlysuspended from the frame of the instrument. Adjustablemechanical-electrical pick-ups are provided at desired locationsrelative to the various rods and their support for the purpose ofchanging mechanical vibrations into electric vibrations. Strikers can beprovided for selectively activating the vibrators, the strikers beingarranged so that there is a magnetic brake effect which permits thestriker to hit the particular vibrator involved with the desired action.Preferably, the rods are provided with an intermittently effectivedamping arrangement which becomes increasingly effective or acceleratesthe damping after the vibrator is set into vibration such as describedin detail in applicants copending application erial No. 229,380, filedJune l, 1951.

In a further aspect of the invention, a circuit arrangement can be usedfor the purpose of attenuating low frequency vibrations in the rodsproducing high notes so that the low frequencies in the lower notes willbe in a desired strength relative to the high notes.

When the partials of the rods are assembled and are tuned so as to be inthe proper relationship, occasionally, it will be found that aparticular partial undesirably will cause vibration of the entire blockand system. When this occurs, means must be provided to detune thesupporting block and system so as to eliminate such undesirablevibrations. In the present invention, this is accomplished by providingmeans for selectively adding inertia to the system as needed.

These and other objects, advantages and features of the invention willbecome apparent from the following description and drawings:

Fig. l is a fragmentary side view with portions of the device cut away;

Fig. 2 is a fragmentary top view of the vibrator supporting block ofFig. l;

Fig. 3 is a side View of Fig. 2 with portions broken away and insection;

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2,770,994 Patented Nov. 20, 1956 ICC Fig. 4 is a fragmentary Viewlooking in the direction 4-4 of Fig. 2;

Fig. 5 is a top schematic View of the assembly of Fig. l;

Fig. 6 is a schematic wiring diagram of one form of a circuit which canbe used; and

Fig. 7 is a detail enlarged view of one form of plunger.

Referring to Fig. l, supporting block 10 may have xedfree vibrator rods11 carried in slots 12 (Figs. 1-4), the connection of said fixed-freerods with said block being made such that the rods are acousticallyintegral therewith. Block 10 can be suspended by means of resilientmembers 13 from the main frame 14 of the instrument. Resilient members13 may be fastened to block 10 in any suitable manner, such as by screws15, the members being connected to the main frame 14 by means of screws16.

The striker mechanism assembly is carried on plate 18, plate 18 beingsuitably supported from block 10. In the illustrated form of theinvention, resilient C shaped spring members 17 are fastened by screws19 and 20 to the block 10 and plate 1S respectively so as to resilientlysupport the striker assembly. A striker is provided for each of therods, the striker being selectively energized by means of a conventionalkeyboard switching arrangement which can be operated or played asdesired. Preferably, a source of suitable alternating current isutilized for operating the solenoids.

Referring to Fig. 3, for example, upon energization of solenoid 21, thestriker plunger 22 will be projected upwardly until it strikes its rod11 as indicated in the dotdash lines and then Will move away from therod. The plunger has a portion 21A (Fig. 7) thereof made of a magneticmaterial, the upper portion 21B being nonmagnetic. The dimensions arechosen so that the plunger upon activation of the solenoid will move upand overshoot suiiicient to strike the rod once and then come to restIaway from the rod. A magnetic brake concentrates the magnetic forceoperating the striker plunger so as to produce the desired strikingforce and retracted position of the plunger after the rod has beenstruck and while the solenoid is energized. Upon release of an operatedkey, the plunger will return to its normal position as illustrated infull lines in Figure 3. Suitable connectors can be provided forconnecting the keyboard to the various strikers. As an example of onetype of construction, the non-magnetic portion 21B can be in the form ofa hollow eyelet with a ared end. The flared end limits the amount thatthe plunger can move downwardly in the solenoid when the solenoid isdeenergized.

Located above each of the rods 11 is an adjustable collector 23. Thecollector may have a widened face 24 which is adjustably spaced relativeto its rod, a slot being provided in one end of the collector forfacilitating adjustment by a screwdriver or the like. The collectorplate is screw-threadedly mounted in apertures in block 10.

As described in detail in applicants copending application, Serial No.229,380, ilexible members 25, such as nylon threads, may be looselymounted in apertures adjacent an end of each of the rods. Flexiblemembers 25 are arranged so that a portion thereof normally rests on athreaded rod 26, threaded rod 26 being fastened to frame 14 by nuts 27.When a vibrator rod is set into vibration, its exible element will jumprelative thereto and intermittently come into contact therewith, thusserving to intermittently damp the vibrations of said rod and theflexible element also will jump clear of threaded rod 26. As theamplitude of the vibrator decreases, the flexible element again willcome into contact with threaded element 26 and accelerate the damping ofthe vibration.

Frequently, it is desirable in a musical instrument of the typedescribed employing fixed-free rods, to attenuate the low frequencyvibrations in the high notes, such attenuation not being desirable inthe lower notes. manner of accomplishing this is illustrated in Figure 6wherein 28B represents the block on which rods 28, 29, 30 and 31 aremounted. Rods 23 and 29 represent the higher notes, such as those in therange of high G and rods 30 and 31 can be the notes in the range of lowFor example, high G to Cit below high G can be considered to be highernotes as far as a typical grouping is concerned.

Collector plates 28A and 29A are connected by lead 32 through resistor33 to the polarizing source of Voltage for the vibrator system. Lead 34connects grid 35 of the rst amplier tube 36 through a conventionalblocking condenser 37. The low note rods 30 and 31 have their collectorplates 30A and 31A connected to the polarizing voltage through anadditional resistor 38. Thus, the polarizing voltage is furnished forthe collector plates of the lower note rods through resistor 33 andresistor 38. In such an instance, the load impedance is lower for thehigh notes and this will serve to attenuate the lower vibrationstherein. The additional resistance in the load circuit for the lowernotes makes the load impedance of this circuit such that it does notperceptibly attenuate the lower vibrations therein so that the lowernote circuit is substantially less frequency selective than the highnote circuit.

In the form shown, the high notes can be connected together by flexiblestrips 40 (Fig. 2), only the upper one being shown. The lower notes areconnected to each other by flexible strip 4l bridging the outer groupsof low notes. In addition to the strip 41, strips 42 and 43 areinterwoven in the projecting upper ends or shanks of the collectors soas to join them. Resistor 44 corresponds with resistor 38 of Fig. 6.

After the rods 11 and other parts have been assembled relative to base10, it is necessary to tune the rods so that they produce the correcttone in the loud-speaker LS (Fig. 6) when struck. It sometimes occursthat a particular partial present in one of the vibrating rods willcause undesirable vibration or resonance and interference patterns inthe block il@ which will be accentuated in the sound system. In order toprovide a way for detuning the system easily in the assembling andtuning operation, the device can be constructed to permit selectiveaddition of weights or mass to the block` One manner of accomplishingthis is to provide threaded apertures 45 in the block l0 for selectivelyreceiving weights or plugs. When it is found that an undesirablevibra-tion is present, one or more weights or plugs can be suitablyfastened in the various apertures as needed to eliminate the undesirablevibration.

A simplied musical bell tone instrument can be made by following theteachings of the present invention. It is to be understood that detailsof construction can be changed without departing from the spirit of theinvention except as defined in the appended claims.

What is claimed is:

l. In an electric music instrument, the combination including anelongated supporting block having a plurali-ty of fixed-free rodsmounted at longitudinally spaced points on said block, a plurality ofapertures therein at predetermined locations over the length of theblock, striker mechanism for selectively striking said vibrators,electric pick-up means adjacent each of said rods, amplifying meansconnected to said pick-up means, loudspeaker means connected to saidamplifying means, and means selectively placeable in said apertures fordetuning undesired resonant vibrations in any part of said block tocontrol tone interference patterns.

2. In an electric music instrument having at least one vibrator, thecombination including a solenoid having an aperture therethrough, and astriker plunger for striking said Vibrator, said plunger comprising aseparate nonmagnetic material hollow head with a ared top, and aseparate magnetic shank fastened thereto, said flared One i head actingas a stop in cooperation with said aperture and solenoid establishingthe return position of the plunger in said solenoid when the solenoid isdeenergized.

3. In an electric music instrument, the combination including asupporting block, a plurality of vibrators carried by said block,electric pick-up means for each vibrator mounted in said block andhaving a collecting face in proximity to its vibrator, each of saidpick-up means having shanks in spaced relationship to each other andsaid block, first undulated exible metal strip means interwoven on saidShanks so as to contact diametrically opposed surfaces on adjacentlylocated Shanks, and second undulated exible metal strip means interwovenon said shanks so as to contact diametrically opposed surfaces onadjacently located shanks which are not contacted by said rst metalstrip means, said first and second metal strip means serving toelectrically interconnect and structurally support said Shanks.

4. In an electric music instrument, the combination comprising asupporting block, a plurality of vibrators carried by said block, saidvibrators including a group of vibrators producing high notes made up ofa plurality of partials and a group of vibrators producing low notesmade up of a plurality of partials, selectively operable actuating meansfor causing said vibrators to vibrate, an electric pick-up of thevariable capacitance type for each vibrator mounted in said block andhaving a collecting face in proximity to its vibrator, each of saidpick-ups having Shanks in spaced relationship to each other and saidblock, separate collector means for electrically interconnecting therespective pick-ups in each of said groups of vibrators, said collectormeans comprising undulated flexible metal strip means interwoven on theshanks of the pick-ups in its vibrator group to electricallyinterconnect them, an amplifier, electro-acoustical means connected t0the output of said amplifier, means for electrically connecting thecollector means of the high note producing group of vibrators with theinput of said amplier, and resistor means electrically connecting thecollector means of the high note producing group of vibrators with thecollector means of the low note producing group of vibrators such thatthe low frequency partials produced by the high note producing vibratorsonly are attenuated.

5. In an electric music instrument, the combination comprising aplurality of vibrators each producing a different note made up of aplurality of partials, said plurality of vibrators including a group ofvibrators producing high notes and a group of vibrators producing lownotes, separate actuating means for each of said vibrators for causingsaid vibrators to vibrate, an electrical pick-up of the variablecapacitance type for each of said vibrators, separate collectormeans forelectrically interconnecting the respective pick-ups in each of saidgroups of vibrators, an amplifier, electro-acoustical means connected t0the output of said amplifier, means for electrically connecting thecollector means of the high note producing group of vibrators with theinput of said amplier, first resistor means connected at one end thereofto said lastnamed connecting means, a source of polarizing voltageconnected between said vibrators and the other end of said rst resistormeans, and second resistor means electrically connecting the collectormeans of the high note producing groupA of vibrators with the collectormeans of the low note producing group of vibrators, said rst and secondresistor means combining with the capacities of said pick-ups to formfrequency selective means for attenuating the low frequency partialsproduced by the high note producing vibrators.

References Cited in the le of this patent l v UNITED STATES PATENTS486,013 Wuest, Ir. Nov. 8, 1892 (Other references on following page)UNITED STATES PATENTS Sheldon June 21, 1910 Young May 25, 1915 BergersonAug. 22, 1916 Hunt 1an. 14, 1930 Jacobs June 27, 1933 Jacobs Oct. 31,1933 Severy Nov. 14, 1933 Lesti Jan. 7, 1936 Hosche Apr. 5, 1939Miessner Aug. 8, 1939 6 Miessner May 14, 1940 Edwards July 2, 1940 HingsDec. 27, 1949 Fleury June 6, 1950 Merrill, Jr. May 8, 1951 Zuck Oct. 2,1951 Schmidt Oct. 23, 1951 FOREIGN PATENTS Great Britain May 15, 1947

